title: Neuroprotection by cord blood stem cells against glutamate-induced apoptosis is mediated by Akt pathway.
abstract: The neurotransmitter glutamate mediates excitatory synaptic transmission in the brain and spinal cord. In pathological conditions massive glutamate release reaches near millimolar concentrations in the extracellular space and contributes to neuron degeneration and death. In the present study, we demonstrate a neuroprotective role for human umbilical cord blood stem cells (hUCB) against glutamate-induced apoptosis in cultured rat cortical neurons. Microarray analysis shows the upregulation of stress pathway genes after glutamate toxicity of neurons, while in cocultures with hUCB, survival pathway genes were upregulated. Real time-PCR analysis shows the expression of genes for NMDA receptors after glutamate toxicity in neurons. The neuroprotection of hUCB against glutamate toxicity is similar to the application of the glutamate receptor antagonist MK-801. Cocultures of hUCB protected neurons against glutamate-induced apoptosis as revealed by APO-BrdU TUNEL and FACS analyses. Immunoblot analysis shows that apoptosis is mediated by the cleavage of caspase-3 and caspase-7 in glutamate treated neurons. Cocultures with hUCB indicate the upregulation of Akt signaling pathway to protect neurons. Blocking of the Akt pathway by a dominant-negative Akt and using Akt-inhibitor IV, we confirm that the mechanism underlying hUCB neuroprotection involves activation of Akt signaling pathway. These results suggest the neuroprotective potential of hUCB against glutamate-induced apoptosis of cultured cortical neurons.
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine, Peoria, IL 61656, USA.
authors.forename: Venkata Ramesh
authors.initials: VR
authors.lastname: Dasari
authors.forename: Krishna Kumar
authors.initials: KK
authors.lastname: Veeravalli
authors.forename: Kay L
authors.initials: KL
authors.lastname: Saving
authors.forename: Meena
authors.initials: M
authors.lastname: Gujrati
authors.forename: Dan
authors.initials: D
authors.lastname: Fassett
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Klopfenstein
authors.forename: Dzung H
authors.initials: DH
authors.lastname: Dinh
authors.forename: Jasti S
authors.initials: JS
authors.lastname: Rao
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D018920:Coculture Techniques; D016291:Dizocilpine Maleate / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology; D015870:Gene Expression; D018698:Glutamic Acid / Q000633:toxicity*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D009474:Neurons / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013234:Stem Cells / Q000502:physiology*
chemical_list: D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D053179:Caspase 7